This invention relates generally to processes for creating strains in component parts and more particularly to impressing internal stress in fiber-reinforced plastic layers.
Certain component parts such as torsion-bars or hollow shafts which have low weight and poor sound transmission often develop cracks during use due to tensile stresses exerted perpendicular to the fiber orientation, so that the resistance to fatigue of the component part is reduced. These cracks occur after a relatively short period of time.
The German patent DE-OS No. 28 42 531, discloses a process of the above type whereby a first tube layer of fiber glass-reinforced plastic is produced and in a hardened state, axially pressure-stressed by an outside force. Thereafter, a second tube layer with a fiber glass winding of a defined orientation is applied onto the first layer and hardened. After hardening of the second tube layer, the outside force exerted on the first tube layer is discontinued. The impression of internal stresses by this known process counteracts the decrease in fatique from the occurrence of cracks and can be applied only during the main production of the component part.